Apparatus for stretching and smoothing a natural tobacco leaf

ABSTRACT

An apparatus for stretching and smoothing tobacco leaves comprising an intermittently advanced, air-permeable, stretchable conveyor belt for carrying leaves from a receiving station to a smoothing station to a stretching station. A moist leaf placed and aligned on the belt at the receiving station, and held thereon by suction through the belt, is advanced to the smoothing station where it is clamped by its central vein and subjected to diverging air currents that flutter the edges of the leaf outwardly. Suction is then reapplied to hold the leaf and it is advanced to the stretching station where the belt is transversely stretched to thereby stretch the leaf as well.

United States Patent [1 1 Wallenborn [451 Sept. 18,1973

[75] Inventor: Nils Wallenborn, Spanga, Sweden [73] Assignee: Arenco Aktiebolag,

Stockholm-Vallingby, Sweden [22] Filed: Dec. 11, 1970 [21] Appl. No.: 97,348

Related U.S. Application Data [62] Division of Ser. No. 853,418, Aug. 27, 1969, Pat. No.

Rundell et a1. 131/123 Rundell 131/123 Primary ExaminerRobert W. Michell Assistant Examiner-John F. Pitrelli [57] ABSTRACT An apparatus for stretching and smoothing tobacco leaves comprising an intermittently advanced, airpermeable, stretchable conveyor belt for carrying leaves from a receiving station to a smoothing station to a stretching station. A moist leaf placed and aligned on the belt at the receiving station, and held thereon by suction through the belt, is advanced to the smoothing station where it is clamped by its central vein and subjected to diverging air currents that flutter the edges of the leaf outwardly. Suction is then reapplied to hold the leaf and it is advanced to the stretching station where the belt is transversely stretched to thereby stretch the leaf as well.

6 Claims, 8 Drawing Figures PATENTED E 3.759.269

' sum 2 [IF 3 so as 33 11 19 29 PATENTEBsE-Hamn SHEET 3 OF 3 APPARATUS FOR STRETCHING AND SMOOTHING A NATURAL TOBACCO LEAF CROSS REFERENCES TO RELATED APPLICATIONS This application is a divisional application based on application, Ser. No. 853,4l8, filed Aug. 27, I969. Application, Ser. No. 853,418 matured into US. Pat. No. 3,612,067 subsequent to the filing of the present application.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an apparatus for stretching and smoothing a natural tobacco leaf and comprises air-flow members adapted to expose the tobacco leaf fixed on a leaf support to an air-stream directed from the central vein of the leaf to the edges thereof and suction means for retaining the leaf in an expanded condition after the stretching step.

Description of the Prior Art In known apparatuses which have been coupled together with stripping machines the demands on stretching the leaf are low and therefore the leaf, after a first stretching treatment, is transferred in a free state to a suction conveyor or the like for further advance to the stripping knives. Here the leaves rapidly regain a relatively creased condition and must, if they are to be fed to means for cutting out wrappers for cigars, be inserted into a smoothing device comprising rotating brushes or suction cloths which smooth the leaf by'mechanical action. However, if an effective smoothing shall be brought about, the action of these devices normally causes damage to the highly vulnerable, moist leaves, and in addition, it is not possible to bring about a flattening of leaf portions, bent inwardly under the leaf.

SUMMARY OF THE INVENTION This invention provides an apparatus for stretching a tobacco leaf and retaining it stretched during the entire stretching operation until final working or storing while totally avoiding the risk of the leaf becoming damaged, irrespective of how various portions of the leaf are folded onto one another.

BRIEF DESCRIPTION OF THE DRAWINGS Further objects and advantages of the invention will become apparent from the following description considered in connection with the accompanying drawings which form part of this specification and in which:

FIG. 1 shows an examplary embodiment of the apparatus viewed from above with certain portions removed for the sake of clarity,

FIG. 2 shows a section through the apparatus of FIG. 1, taken along the line IIII,

FIG. 3 shows a section through the apparatus of FIG. 1, taken along the line III-III,

FIG. 4 shows a section through the apparatus of FIG. 1, taken along the line IVIV,

FIG. 5 shows a section through the apparatus of FIG. 1, taken along the line V-V,

FIG. 6 is a side view of an apparatus for stretching natural tobacco leaves coupled to a stripping machine,

FIG. 7 is a top view of the apparatus of FIG. 6 and FIG. 8 is a sectional view following the line VIII- VIII of FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENT The embodiment shown in the drawings comprises three stations A, B and C, of which stations A and B illustrate the basic invention and which may be utilized as much without the station C for feeding stretched leaves to a stemming machine, for example. Station C is utilized in those cases where a strong stretching of the tobacco leaf already flattened in the station B is required. The expression tobacco leaf"- used herein is intended to mean both a non-stemmed natural tobacco leaf, i.e. a leaf having a central vein, and a leaf half or other major part of a' natural tobacco leaf, such as a cigar binder or a wrapper.

The apparatus shown in FIGS. 1 to 5 is provided with an air-permeable belt 1 of at least transversally stretchable material, such as a perforated rubber belt, a woven belt or the like. If the station C is not utilized, the belt need not be stretchable, as will become evident later, but may consist of a perforated steel band or an air belt of other non-stretchable material. The belt 1 is guided over rollers of which roller 2 only is shown. Roller 2 is driven in the direction of the arrow, FIG. 2, from a power source not shown, and thus the upper part of the belt 1 moves in the direction of the arrow shown at station A, FIG. 1. In the embodiment shown, the device is driven intermittently in such a manner that a tobacco leaf 3 during rest of the belt is placed on the belt 1 at the station A and thereafter dun'ng motion of the belt 1 is fed into station B.

In the embodiment shown, the upper part of the belt 1 is guided by freely rotating support rollers 4. The support rollers 4 at station A are mounted in the side walls of a vacuum box 5 positioned below the upper part of the belt 1, and connected through a suction tube 6 to a vacuum source, not shown.

At station B, the rollers 4 are divided into two equal parts and the stub axles of the rollers are mounted in the walls of a vacuum box 7 (FIG. 4) and in a coupterpressure rail 8 extending in the longitudinal direction of the belt 1. Vacuum box 7 is connected to a vacuum source, not shown, through a suction pipe 9 provided with a throttle valve 10.

The rollers 4 at station C are mounted in the walls of a vacuum box 11, which through a suction pipe 12 is in connection with a vacuum source, not shown.

In order to obtain an additional stretching of tobacco leaf 3 at station C, the belt 1 in the embodiment shown is guided laterally. The edge portions of the belt 1 are provided with a longitudinally extending holding means 13 in the shape of bulbous projections or the like on which guide pins 14 are secured. The guide pins 14 are guided in grooves 15 formed in two guide rails 16. On both sides of the belt 1, the grooves 15 extend parallel to one another and between stations A and B are spaced apart a first distance from one another, whereas at station C, the distance is increased so as to cause a transverse stretching of the belt 1.

Disposed at the station B over the upper part of the belt 1 is a device for stretching the leaf. In the embodiment shown, the leaf stretching device consists of a suction box 17, which is wholly open towards the belt 1. On both sides of the belt 1, the suction box 17 is equipped with two suction tubes l8, 19, which are provided with throttle valves 20,21 (FIG. 4). By means of a tie rod 22, the suction box 17 can be lifted and low ercd. The tie rod 22 has its upper end connected to one end of a lever 23 (FIG. 4) which is fixed at 24 and the other end of which carries a cam follower 25. The follower 25 is forced by a pressure spring 26 positioned between the lever 23 and a fixed bearing 27 against a cam 28 which is mounted on a shaft 29 driven from a power source not shown. The top plate of the suction box 17 on which the tie rod 22 is rigidly secured is further equipped with two guide bars 30 running in stationary guides 31, the purpose of which to guide the box 17 during the movement thereof. Mounted on the under side of the box plate is a pressure rail 32 facing the counterpressure rail 8 (FIGS. 2 and 4), preferably made of some resilient material such as rubber, and which in the working position of the suction box 17, shown in FIG. 4, bears against the counterpressure rail 8. In the embodiment shown, the box plate is further formed with inlet suction openings 33 located approximately in the centre line of the box 17 and disposed substantially over the entire length of the box 17 in parallel with the direction of feed of the belt. The side walls of the box 17 extending in the longitudinal direction of the belt 1 form elongated suction nozzles 34. When the throttle valves 20, 21 are open, air is sucked through the holes 33 and the nozzles 34 into the tubes 18 and 19 and an air stream is created which substantially is directed, in the embodiment shown, from the central vein 35 of the tobacco leaf 3 toward the edges thereof.

The apparatus shown operates in the following manner.

A moistened natural tobacco leaf which is to be stretched is at station A laid on the belt 1 when at rest, markings 36 arranged on the belt serving as guide points for centering the central vein 35 of the leaf 3. This central locating operation is not particularly critical. By means of the vacuum box 5, an air stream is continuously drawn through the belt 1 and the leaf not yet flattened is retained in correct position by suction. During this step, the suction box 17 in station B is in its lowered position, and the throttle valves 10, 20 and 21 have the positions shown in FIG. 4. By means of a conventional control mechanism, not shown, the throttle valve is thereupon opened and the throttle valves and 21 are closed, whereby a processed leaf is retained by suction on the belt 1 at station A. Shaft 29 is thereafter rotated and the cam '28 rotates in the direction of the arrow (FIG. 4), whereby the lever 23 is turned clock-wise and raises the tie rod 22 and, thus, the suction box 17 from the belt, e.g. 1 cm.

Thereafter, the conventional driving mechanism not shown drives roller 2 and belt 1 one step forwards, so that the tobacco leaf 3 fed in at station A is advanced below the suction box 17 at station B, whereupon the belt 1 is stopped and the box 17 lowered to the position shown in FIG. 4. The leaf 3 will thereby have the central vein 35 clamped between the rail 8 and the rail 32, the central vein 35 being retained firmly in the clamped position. Simultaneously, throttle valves 20 and 21 are opened and throttle valve 10 is closed and the leaf portions on either side of the vein 35 are each exposed to a strong air stream directed outwardly. By these two air streams, the two leaf halves are caused to flutter, so that all tuckings and foldings are straightened out and in such a manner that a stretching from the central vein 35 towards the edges is obtained. After the stretching has been completed within the course of a first time interval of some seconds, the automatic control device, not shown, of the apparatus opens the throttle valve 10 during a second time interval, the throttle valves 20 and 21 being closed simultaneously therewith or immediately thereafter. The shaft 29 is caused to rotate, and the cycle described earlier for lifting the suction box 17 and feeding a leaf recently put on at the station A into station B is repeated. The stretched leaf 3 at the station B is conveyed while retained by suction on the belt 1 to station C. Due to the fact that the spacing between the grooves 15 increases between stations B and C, the belt 1 will expanded laterally and, thus, also leaf 3 will be stretched laterally.

As already mentioned, the station C is utilized only when a very stong stretching of the leaf is required. It is obvious that the apparatus can be modified in various manners without departing from the inventive idea. Thus, it is possible, for example, during the stretching of the leaf at the station B to use the vacuum box 7 as a source of compressed air in order to treat the underside of the leaf 3 also be means of an air stream. Fur ther the belt 1 can by provided with fixing members of the clamp type, by means of which one end of the central vein is mechanically secured onto the belt, whereby the markings 36 and in some cases also the vacuum box 5 can be dispensed with.

The apparatus may also be driven continuously, in which case a constant spacing always exists between the belt 1 and the suction box 17 in order to allow the leaves to pass through freely. Of course, in this case, the mechanism for lifting and lowering the suction box to the open position and the position substantially sealing against the belt 1 is not required. In both cases where a stretching station C is used, it is further possible instead of stretchable belts to use belts of metal or rigid plastic consisting of longitudinally extending disc displaceable transversally in relation to one another.

The apparatus shown in FIGS. 6 to 8 is provided with a deposit table 37 for tobacco leaves, which in the present case are non-stemmed, e.g. retaining their central vein. The table 37 which is intended to render easier correct feeding into the stretching apparatus is formed with a central row of suction holes 38. The table 37 is formed as a suction box and communicates via a conduit 39 with a suction source not shown here. The tobacco leaf 3 is manually deposited on the table 37 with its central vein over the suction holes 38. The leaf is thereby retained in position and conveyed onto a conveyor belt 40. The conveyor belt 40 is laid over two belt pulleys 41, 43 of which at least one is driven. The belt 40 passes through a groove 44 in a box 45 which supplies comperssed air to a blow-pipe table 46. The blow-pipe table 46 is formed with a central groove into which the upper portion of the conveyor belt 40 is advanced. In the embodiment shown, the upper, supporting surface of the belt 40 is located slightly above the surface of the table 46. Two pressure belts 47, 48 parallel to one another and to the belt 40 cooperate with the upper portion of the belt 40 which is aligned with the row of suction holes 38. The pressure belts are spaced from one another by such a distance and cooperate with the belt 40 in such a manner, that the central vein of a tobacco leaf 3 fed from the table 37 will be situated between the belts 47 and 48 and clamped rigidly against the belt 40. The belts 47, 48 are laid over belt pulleys 49, 51B, of which the pulley 49 is driven in the direction of the arrow by means ofdriving members not shown here.

A second, upper blow pipe table 51 is disposed parallel to and spaced from the first, lower blow-pipe table 46 and connected to an upper box 52 which supplies compressed air. The compressed air is supplied to the lower box 45 through a conduit 53 which is connected to a source for compressed air not shown and preferably controllable so that the quantity of supplied compressed air can be varied. The box 52 for compressed air is connected via a conduit 54 to a source of compressed air not shown which may be the same as that for the box 45. Preferably, control means are disposed between the source for compressed air and the two boxes 45 and 52 such that the quantities of air supplied to each of the boxes can be adjusted independently of one another.

Blowing openings 55 are formed in the blow-pipe tables 46 and 51 at least within the zone which is occupied by an introduced tobacco leaf 3, said blowing openings producing air streams directed from the central vein of the leaf outwards toward the edges of the leaf and acting on both the underside and the upper side of the leaf. As will be seen best from FIG. 8, the openings 55 have the shape of channels directed from the central line of the tables 46,51, respectively, to the outer edges thereof. When the source (not shown) for the compressed air is in operation, a tobacco leaf, which has been fed from the table 37 onto the continuously operating conveyors 40 and 47,48 will thus be introduced between the blow-pipe tables 46 and 51 and be exposed to two air streams, one from the blow-pipe table 46 acting on the under side of the tobacco leaf and one from the blow-pipe tabel 51 acting on the upper or top side of said leaf. The air stream from the blow-pipe table 46 is divided into two partial streams each of which acts from the central enine retained by clamping between the conveyor belts towards the edges of the leaf, and the air stream from the blow-pipe table 51 is divided into two similar air streams. Thereby the leaf will be strongly fluttered and stretched in the desired manner. Even when the leafis folded strongly and non-flexible a smoothing and stretching will be obtained by the air streams which are adjustable independently of one another and which act both on the upper side and the under side of the leaf.

The tobacco leaf 3 is fed continuously through the leaf stretching apparatus and discharged therefrom onto a conveyor consisting of two perforated or airpermeable conveyor belts 56,57, which are laid over conveyer rollers 42 and 68, of which the roller 68 is driven from a driving device not shown. The conveyer belts 56, 57 form between themselves a gap 58 for the conveyer belts 47, 48 and for stripping knives cooperating with one another for de-stemming the tobacco leaf, i.e. for cutting away the central vein thereof. A suction box 59 which through a conduit 60 communicates with a suction source not shown cooperates and is situated below the upper portions of the conveyor belts 56,57. The stripping knives consist of two lower, driven circular knives 61, 62 spaced from one another by a distance approximately corresponding to the breadth of the stem of the tobacco leaf. A driven circular feeder knife 63 is positioned above and cooperates with the circular knives 61, 62. The knives rotate in the shown directions. When the stretched tobacco leaf3 is discharged from the blow-pipe tables 46, 51 by the conveyer belts 40,47, 48 it is fixed by suction in its stretched state onto the conveyer belts 56,57 which are advanced in the direction of the arrow shown in FIG. 7 and with the same speed as the belts 40, 47, 48. When the central vein of the leaf is introduced between knives 61,62,63 it is continuously cut away, leaving two stretched leaf halves remaining on the conveyor 56,57, as is shown at the right in FIG. 7, which leaf halves can be directly transferred by means not shown here to, e.g. a cigar wrapping machine.

What is claimed is:

1. An apparatus for stretching and smoothing a natural tobacco leaf including air-flow members adapted to expose the leaf fixed on a leaf support to an air-stream directed from the central vein of the leaf towards the edges thereof and suction members for retaining the leaf in expanded condition after the stretching step, said apparatus comprising:

a first blow-pipe table having a plurality of air openrngs,

a second blow-pipe table, also having a plurality of air openings, said second blow-pipe table being disposed above and facing said first blow-pipe table at a distance permitting passage of tobacco leafs therebetween, and

compressed air devices connected to the air openings of said first and second blow-pipe tables,

whereby a leaf passing between said first and second blow-pipe tables may be subjected to an air flow which acts partly on the upper side of the leaf and partly on the under side thereof.

2. The apparatus as claimed in claim 1, characterized in that each of the two blow-pipe tables is provided with a central gap, that a first belt conveyer is disposed in the gap of the first blow-pipe table, said first belt conveyor cooperating with a second belt conveyer disposed in the gap of the second blow-pipe table which two belt conveyers are devised to catch the central vein of a tobacco leaf and to convey the tobacco leaf into the interspace between the blow-pipe tables.

3. The apparatus as claimed in claim 2, characterized in that the first belt conveyor comprises an endless belt, which is laid over belt pulleys and has a breadth exceeding the breadth of the central vein of the tobacco leaf and that the second belt conveyor comprises two endless belts parallel to one another and which are laid over belt pulleys and are disposed spaced from one another by a distance substantially corresponding to the breadth of the central vein, the disposition being such that the tobacco leaf is fixed by clamping between the two belt conveyers with the central vein between the two belts running in parallel to one another.

4. The apparatus as claimed in claim 2, characterized in that the belt conveyers are adapted to operate continuously for feeding tobacco leaves between the blowpipe tables and that the compressed air devices connected to the air openings of the blow-pipe tables are adapted to supply compressed air continuously.

5. The apparatus as claimed in claim 1, characterized by a suction conveyer connected to the discharge side of the blow-pipe tables to receive the stretched tobacco leaf and fix it by suction in its stretched state.

6. The apparatus as claimed in claim 5, characterized by a knife mechanism arranged stationarily in the suction conveyer to cut off the central veine of the tobacco leaf during transportation of the leaf on the suction conveyer.

UNITED STATES PATENT OFFECE CERTIFICATE OF QURRECT'ION Patent No. 7 9, 69 Dated September 18, 1973 Inv n Nils W ALLENBORN It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the Heading:

The claim to priority was omitted. Please insert the following:

- Priority Data Sweden 14923/68 November 4, 1968- Signed and sealed this 19th day of February 19714.!

(SEAL) Attest: M M

EDWARD M.FLETGHER,JR. c. MARSHALL DANN Attesting Officer Commissioner of Patents FORM Po-1050 (10-69) uscoMM-oc 6O376-P69 UiS. GOVERNMENT PRINTING OFFICE I969 0-366-334, 

1. An apparatus for stretching and smoothing a natural tobacco leaf including air-flow members adapted to expose the leaf fixed on a leaf support to an air-stream directed from the central vein of the leaf towards the edges thereof and suction members for retaining the leaf in expanded condition after the stretching step, said apparatus comprising: a first blow-pipe table having a plurality of air openings, a second blow-pipe table, also having a plurality of air openings, said second blow-pipe table being disposed above and facing said first blow-pipe table at a distance permitting passage of tobacco leafs therebetween, and compressed air devices connected to the air openings of said first and second blow-pipe tables, whereby a leaf passing between said first and second blow-pipe tables may be subjected to an air flow which acts partly on the upper side of the leaf and partly on the under side thereof.
 2. The apparatus as claimed in claim 1, characterized in that each of the two blow-pipe tables is provided with a central gap, that a first belt conveyer is disposed in the gap of the firSt blow-pipe table, said first belt conveyor cooperating with a second belt conveyer disposed in the gap of the second blow-pipe table which two belt conveyers are devised to catch the central vein of a tobacco leaf and to convey the tobacco leaf into the interspace between the blow-pipe tables.
 3. The apparatus as claimed in claim 2, characterized in that the first belt conveyor comprises an endless belt, which is laid over belt pulleys and has a breadth exceeding the breadth of the central vein of the tobacco leaf and that the second belt conveyor comprises two endless belts parallel to one another and which are laid over belt pulleys and are disposed spaced from one another by a distance substantially corresponding to the breadth of the central vein, the disposition being such that the tobacco leaf is fixed by clamping between the two belt conveyers with the central vein between the two belts running in parallel to one another.
 4. The apparatus as claimed in claim 2, characterized in that the belt conveyers are adapted to operate continuously for feeding tobacco leaves between the blow-pipe tables and that the compressed air devices connected to the air openings of the blow-pipe tables are adapted to supply compressed air continuously.
 5. The apparatus as claimed in claim 1, characterized by a suction conveyer connected to the discharge side of the blow-pipe tables to receive the stretched tobacco leaf and fix it by suction in its stretched state.
 6. The apparatus as claimed in claim 5, characterized by a knife mechanism arranged stationarily in the suction conveyer to cut off the central veine of the tobacco leaf during transportation of the leaf on the suction conveyer. 